JP7708049B2 - Electrode manufacturing method - Google Patents

Description

This disclosure relates to a method for manufacturing an electrode.

One known method for manufacturing electrodes is to roll a sheet in which an electrode mixture is applied onto a long metal foil.

For example, Patent Document 1 discloses a method for pressing a battery electrode having a coated portion coated with an electrode active material and an uncoated portion not coated with the electrode active material. Patent Document 2 discloses a roll pressing method using a roll press machine equipped with a wrinkle prevention device that suppresses the occurrence of wrinkles caused by the roll pressing operation in the coated and uncoated portions of the electrode plate.

Patent No. 5760366 JP 2019-102172 A

As described above, when pressing a sheet having coated and uncoated areas, the coated and uncoated areas may be pressed separately to adjust the difference in elongation so as to prevent wrinkles from occurring. Also, the uncoated areas may be roll pressed using an elastic roll to prevent breakage of the uncoated areas when pressed.

The inventors have found that when pressing an uncoated portion using an elastic roll, if the elastic roll runs over the coated portion due to meandering or the like, there is a risk of streaks appearing in the coated portion or the coated portion breaking, which may result in a deterioration in the quality of the resulting electrode.

This disclosure was made in consideration of the above-mentioned circumstances, and its main objective is to provide a method for manufacturing electrodes that can suppress deterioration of quality.

[1]
the method includes: a preparation step of preparing a precursor sheet having a metal foil having a longitudinal direction in a first direction, and a coated portion and an uncoated portion arranged on the metal foil; a coated portion pressing step of pressing the coated portion in a thickness direction while transporting the precursor sheet in the first direction; and an uncoated portion pressing step of pressing the uncoated portion in the thickness direction while transporting the precursor sheet in the first direction, before or after the coated portion pressing step, wherein the coated portion contains an electrode material including at least an active material, and the uncoated portion does not contain the electrode material and is arranged at an end of the coated portion in a second direction perpendicular to the first direction, and the uncoated portion pressing step In the step of rolling, a pair of elastic rolls having a shaft and an elastic body covering the shaft are used to perform roll pressing while applying a compressive force that presses the uncoated portion in the thickness direction, and elastic roll A and elastic roll B are used as the pair of elastic rolls, and the elastic body of the elastic roll A has, when viewed in cross section along the rotation axis of the elastic roll A, a first side, a second side opposite to the first side, a third side extending in a direction intersecting the first side and the second side, a fourth side opposite to the third side, a first connecting portion connecting the first side and the third side, and a second connecting portion connecting the second side and the third side, and a boundary between the first side and the first connecting portion is defined as P a boundary between the third side and the first connecting portion is defined as _Q1 and a boundary between the third side and the second connecting portion is defined as _Q2 , the second connecting portion is defined as a single straight line connecting _{Q1 and Q2} , and the elastic roll _A is positioned such that the third side is located closer _to the coating portion than the fourth side during roll pressing _.

[2]
The electrode manufacturing method described in [1], wherein the length of the elastic body of the elastic roll A is shorter than the length of the elastic body of the elastic roll B in the axial direction of the rotation shaft.

[3]
When observed from the thickness direction, the elastic body of the elastic roll A has a first end and a second end located outside the first end in the axial direction of the rotation shaft, and when observed from the thickness direction, the position of the first end overlaps with the position of the elastic body of the elastic roll B. The electrode manufacturing method described in [1] or [2].

[4]
The method for manufacturing an electrode according to any one of [1] to [3], wherein the elastic roll A is positioned such that, when observed from the thickness direction, the elastic body is in contact with the precursor sheet at a position overlapping with the uncoated portion and is not in contact with the precursor sheet at a position overlapping with the coated portion, and the elastic roll B is positioned such that, when observed from the thickness direction, the elastic body is in contact with the precursor sheet at a position overlapping with the uncoated portion and is in contact with the precursor sheet at a position overlapping with the coated portion.

The present disclosure provides an advantageous effect of providing a method for manufacturing electrodes that can suppress deterioration of quality.

FIG. 1 is a flow diagram illustrating a method for manufacturing an electrode in the present disclosure. FIG. 1 is a diagram illustrating the mechanism in the present disclosure. FIG. 2 is a schematic plan view illustrating a precursor sheet in the present disclosure. FIG. 2 is a diagram illustrating an elastic roll A in the present disclosure. FIG. 2 is a diagram illustrating an uncoated portion pressing step in the present disclosure. FIG. 13 is a diagram showing the results of Experimental Examples 1 and 2.

The manufacturing method of the electrode in this disclosure is described in detail below. Herein, when expressing an aspect in which another member is placed on a certain member, the term "above" is used, unless otherwise specified, to include both a case in which another member is placed directly above a certain member so as to be in contact with the certain member, and a case in which another member is placed above a certain member via another member.

1 is a flow diagram showing an example of a method for manufacturing an electrode in the present disclosure. In FIG. 1, first, a precursor sheet having a metal foil having a longitudinal direction in a first direction and a coated portion and an uncoated portion arranged on the metal foil is prepared (preparation step). The coated portion contains an electrode material including at least an active material. The uncoated portion does not contain the electrode material and is arranged at an end of the coated portion in a second direction perpendicular to the first direction. Next, while the precursor sheet is conveyed in the first direction, the coated portion is pressed in the thickness direction (coated portion pressing step). Then, while the precursor sheet is conveyed in the first direction, the uncoated portion is pressed in the thickness direction (uncoated portion pressing step). In FIG. 1, the uncoated portion pressing step is performed after the coated portion pressing step, but may be performed before the coated portion pressing step. In addition, in the uncoated portion pressing step, a roll press is performed using a predetermined pair of elastic rolls. In particular, in the present disclosure, when viewed in cross section along the axial direction of the rotation shaft, the elastic roll A has a predetermined shape. Here, in this disclosure, "thickness direction" is synonymous with the lamination direction of the metal foil and the coating portion. Also, in this disclosure, "the axial direction of the rotating shaft" may be referred to as "the axial direction" or "the axial direction of the shaft body."

According to the present disclosure, when viewed in cross section along the rotation axis, the elastic roll A has a predetermined first connecting portion and a second connecting portion, so that even if the elastic roll runs onto the coating portion due to meandering or the like, breakage or the like can be suppressed, and deterioration in the quality of the obtained electrode can be suppressed.

As a method for manufacturing an electrode, a method is known in which a precursor sheet in which an electrode mixture is applied onto a metal foil (collecting foil) is pressed. In addition, depending on the presence or absence of an electrode mixture, a difference in elongation rate occurs between the coated and uncoated parts of the metal foil after pressing, which may cause wrinkles in the electrode. In this regard, as in the above-mentioned Patent Document 1, the coated and uncoated parts are pressed separately to suppress the occurrence of wrinkles. In addition, when pressing the uncoated part (metal foil), a pair of elastic rolls may be used to perform roll pressing while applying a compressive force in the thickness direction. By performing such roll pressing, it is possible to apply the above-mentioned compressive force to the uncoated part as well as a deformation force due to deformation of the elastic body. This makes it possible to effectively prevent, for example, breakage of the uncoated part.

Here, the metal foil generally contains a hard tissue harder than the material of the metal foil as an inclusion. By including the hard tissue, for example, the strength of the metal foil can be increased. When a tensile force (horizontal force) is applied to stretch the metal foil, the hard tissue does not deform, but the surrounding metal foil, which is softer than the hard tissue, deforms. As a result, voids are formed around the hard tissue. When multiple voids are connected to each other, breakage is likely to occur. In contrast, in the present disclosure, a pair of elastic rolls are used to perform roll pressing while applying a compressive force in the thickness direction. This allows the uncoated portion to be applied with the above compressive force and a deformation force due to the deformation of the elastic body. As a result, it is considered that the generation of voids around the hard tissue can be suppressed. The above compressive force corresponds to a force in the thickness direction, and the above deformation force corresponds to a force in a direction perpendicular to the thickness direction. In other words, the above deformation force acts in the same direction as the tensile force, and is a force that stretches the metal foil in the same way as the tensile force.

The mechanism in the present disclosure will be described with reference to FIG. 2. FIG. 2(a) is a schematic side view of the electrode sheet and a pair of elastic rolls viewed from the second direction of the metal foil. FIG. 2(b) is a schematic front view of FIG. 2(a) viewed from the first direction of the metal foil, and FIG. 2(c) is an enlarged view of the dotted line portion of FIG. 2(b). Also, FIGS. 2(d) and (e) are schematic front views illustrating a case where the elastic roll runs onto the coating portion. In the present disclosure, as shown in FIGS. 2(a) and (b), a pair of elastic rolls 20A and 20B are used to roll press the uncoated portion 3 while applying a compressive force to press it in the thickness direction. At that time, as shown in FIG. 2(c), the shape of the elastic roll A may be transferred to the elastic roll B by the compressive force, causing distortion in the elastic roll B. Also, due to the nature of roll pressing, a compressive force is applied to the distorted portion again before the distortion is completely eliminated, so the distortion remains during roll pressing. In other words, permanent distortion occurs in elastic roll B. In particular, such distortion is more pronounced when elastic roll A is a stepped roll and elastic roll B is a cylindrical roll (unstepped roll). If the elastic roll runs onto the coating section due to meandering or the like in a state in which such distortion occurs, a difference in the distance (clearance) between elastic roll A and elastic roll B may occur, as shown in Figure 2 (d). In that case, shear stress may concentrate in the area with small clearance, causing streaks in the coating section or causing the coating section to break. As a result, the quality of the obtained electrode may deteriorate.

In this regard, the inventors have focused on the shape of the elastic roll, and have found that, as shown in FIG. 2(c), when the connecting portion connecting the sides of the elastic body of elastic roll A has a curved structure (so-called R-chamfered structure), shear stress is concentrated. And, as explained in FIG. 4 below, if the connecting portion has a predetermined structure (so-called C-chamfered structure), as shown in FIG. 2(e), even if the elastic roll rides up on the coating portion in a state where permanent strain is generated, the distance between elastic roll A and elastic roll B is uniform, and the concentration of shear stress is alleviated. This is because the shape of the permanent strain generated in elastic roll B can be made to correspond to the C-chamfered structure of elastic roll A.

1. Preparation Step The preparation step in the present disclosure is a step of preparing a precursor sheet having a metal foil having a longitudinal direction in a first direction, and a coated portion and an uncoated portion disposed on the metal foil.

Figure 3 is a schematic plan view illustrating a precursor sheet prepared in the preparation process. As shown in Figure 3, the precursor sheet 10 has a metal foil 1 having a longitudinal direction in the first direction D, a coated portion 2, and an uncoated portion 3.

Examples of materials for the metal foil include metals used as materials for battery current collectors. Details are described in "4. Electrodes." The thickness of the metal foil is, for example, 1 μm or more, and may be 10 μm or more. On the other hand, the thickness of the metal foil is, for example, 100 μm or less.

The coated portion of the precursor sheet contains an electrode material that includes at least an active material. The coated portion is disposed on the metal foil. The coated portion becomes an electrode layer through the coated portion pressing process described below.

The electrode material contains at least an active material. The electrode material may also contain at least one of a solid electrolyte, a conductive material, and a binder, as necessary. The active material, conductive material, and binder are described in "4. Electrodes."

The coating portion may be disposed only on the first surface of the metal foil in the thickness direction, or may be disposed on both the first surface and the second surface opposite the first surface.

It is preferable that the coated portion is arranged along the first direction of the metal foil. Also, the coated portion may be arranged continuously along the first direction D of the metal foil 1 as shown in FIG. 3. On the other hand, the coated portion 1 may be arranged intermittently along the first direction D of the metal foil 1.

The thickness of the coated portion is not particularly limited and can be adjusted appropriately according to the desired electrode size. The thickness of the coated portion is, for example, 0.2 mm or more, may be 0.3 mm or more, or may be 0.5 mm or more. On the other hand, the thickness of the coated portion is, for example, 1.5 mm or less, may be 1.0 mm or less, or may be 0.6 mm or less.

The width of the coated portion (the length in the second direction perpendicular to the first direction of the metal foil) is not particularly limited and can be adjusted appropriately according to the desired electrode size. The ratio of the width of the coated portion to the width of the metal foil is, for example, 30% or more, or may be 50% or more, or may be 70% or more. The ratio may be, for example, 90% or less, or may be 80% or less.

The uncoated portion is disposed on the metal foil. The uncoated portion is usually disposed on the same surface of the metal foil as the coated portion. The uncoated portion is, for example, a portion where the metal foil is exposed. As shown in FIG. 3, the uncoated portion 3 in this disclosure is disposed at the end of the coated portion 2 in the second direction perpendicular to the first direction D of the metal foil 1. Although not shown, the uncoated portion may have a protective layer containing resin at the boundary with the coated portion.

The width of the uncoated portion (length in the second direction) is not particularly limited and can be adjusted appropriately according to the desired electrode size. The ratio of the width of the uncoated portion to the width of the metal foil is, for example, 3% or more, and may be 5% or more. On the other hand, the ratio is, for example, 20% or less, and may be 10% or less.

The precursor sheet can be prepared, for example, by applying an electrode material containing a dispersion medium to a metal foil and drying it. Examples of the dispersion medium include organic solvents such as butyl butyrate, dibutyl ether, and heptane. There are no particular limitations on the method for applying the electrode material, and general application methods can be used. In addition, there are no particular limitations on the drying temperature, as long as it is a temperature at which the dispersion medium volatilizes.

The precursor sheet prepared in the preparation step may be, for example, a precursor sheet 10 having, in a plan view, one row of coated sections 2 and two rows of uncoated sections 3 arranged in a striped pattern, as shown in FIG. 3. Although not shown, the precursor sheet may also be a sheet having, in a plan view, N rows (N is an integer of 2 or more) of coated sections and uncoated sections arranged at both ends of each of the N rows of coated sections. In this case, the number of rows of uncoated sections is N+1.

2. Coated portion pressing step The coated portion pressing step is a step of pressing the coated portion in a thickness direction while conveying the precursor sheet in the first direction. The coated portion pressing step may be performed before or after the uncoated portion pressing step described later.

The method and conditions for the coated portion pressing step are not particularly limited as long as the coated portion can be pressed and stretched. An example of a pressing method is a roll pressing method in which the coated portion is roll pressed. For example, the coated portion can be pressed by passing the precursor sheet between a pair of press rolls and pressing the press rolls against both sides of the precursor sheet in the thickness direction.

The compression force in the coated section pressing step is not particularly limited, but is preferably greater than the compression force in the uncoated section pressing step described below. This is because wrinkles may occur in the coated section of the precursor sheet when it becomes wet with the electrode material (slurry) containing a dispersion medium, and a large stretching force is required to remove these wrinkles.

3. Uncoated portion pressing step The uncoated portion pressing step is a step of pressing the uncoated portion in the thickness direction while conveying the precursor sheet in the first direction before or after the coated portion pressing step. In the uncoated portion pressing step, a pair of elastic rolls having a shaft body and an elastic body covering the shaft body are used to roll press the uncoated portion while pressing it in the thickness direction. In the present disclosure, a predetermined elastic roll A and elastic roll B are used as the pair of elastic rolls.

By pressing the uncoated portion, the uncoated portion can be stretched to adjust the difference in elongation with the coated portion. The amount of elongation of the uncoated portion can be adjusted by changing the deformation force caused by the deformation of the elastic body.

First, the elastic roll A used in the uncoated portion press process will be described with reference to FIG. 4. FIG. 4(a) is a schematic cross-sectional view of the elastic roll A taken along the rotation axis. FIG. 4(b) is an external perspective view of the elastic roll A shown in FIG. 4(a). FIG. 4(c) is a schematic cross-sectional view explaining the arrangement of the elastic roll A in the uncoated portion press process.

As shown in Fig. 4(a), the elastic roll A has a shaft body 21 and an elastic body 22. When the elastic roll A (20A) is viewed in cross section along the rotation axis (X direction), the elastic body 22 of the elastic roll A (20A ₎ has a first side _S1 , a second side _S2 opposite to the first side _S1 , a third side _S3 extending from the outer edge of the first side _S1 toward the second side _S2 , and a fourth side _S4 opposite to the third side _S3 . The elastic body 22 also has a first connecting portion _{SL1 connecting the first side S1 and} the third side S3, and a second connecting portion SL2 connecting _{the second side S2 and} the third side _S3 . Then, when the boundary between the first side _S1 and the first connecting portion _SL1 is _P1 , and the boundary between the third side _S3 and the first connecting portion SL1 is _P2 , the second connecting portion _SL1 is a straight line connecting _P1 and _P2 . When the boundary _between the second side _S2 and the second connecting portion _SL2 is _Q1 , and the boundary between the third side _S3 and the second connecting portion _SL2 is _Q2 , the second connecting portion _SL2 is a straight line connecting _Q1 and _Q2 . Note that, as shown in FIG. 4(a) and the like, in the above-mentioned cross-sectional view, the third side _S3 and the fourth side _S4 usually have a portion including the shaft body 21. On the other hand, in the present disclosure, the shaft body portion may not be considered for the third side and the fourth side.

Here, _P2 is located inside _P1 in the radial direction (Z direction) of the elastic roll A. That is, _P1 protrudes from _P2 in the radial direction (Z direction). In other words, a structure (C chamfered structure) is formed in which a corner portion formed by an extension line of the first side _S1 and an extension line of the third surface _S3 is cut by the first connecting portion _SL1 . Similarly, _Q2 is located inside _Q1 in the radial direction (Z direction) of the elastic roll A, and a structure (C chamfered structure) is formed in which a corner portion formed by an extension line of the second side _S2 and an extension line of the third surface _S3 is cut by the second connecting portion _SL2 . In addition, the elastic body 22 of the elastic roll A (20A) may have a third connecting portion connecting the first side and the fourth side, and a fourth connecting portion connecting the second side and the fourth side. The third and fourth connecting portions are similar to the first and second connecting portions.

In addition, in the above cross-sectional view, the angle between the first side and the first connecting part, and the angle between the second side and the second connecting part are each, for example, 100 degrees or more and 170 degrees or less. In addition, in the above cross-sectional view, the angle between the third side and the first connecting part, and the angle between the third side and the second connecting part are each, for example, 100 degrees or more and 170 degrees or less. Note that the above angles refer to the obtuse angle side of the angle between the side and the connecting part in FIG. 4(a).

Also, as shown in Fig. 4(b), when observing the appearance of the elastic roll A, the elastic body 22 of the elastic roll A (20A) usually has a first tapered surface _T1 composed of the above-mentioned first connecting portion and second connecting portion. Also, as shown in Fig. 4(b), the elastic roll A is preferably a so-called stepped roll having the above-mentioned elastic body at both ends of the shaft body in the axial direction X of the rotating shaft. Also, although not shown, when the elastic body has the above-mentioned third connecting portion and fourth connecting portion, it usually has a second tapered surface at a position opposite to the first tapered surface in the axial direction (X direction) of the rotating shaft of the elastic roll A.

Also, as shown in FIG. 4(c), in the uncoated portion pressing step, the elastic roll A (20A) is positioned so that the third side _S3 is located closer to the coated portion 2 side than the fourth side _S4 during roll pressing. As shown in FIG. 4(c), the direction of the rotation axis of the elastic roll A (X direction) is parallel to the first direction D described above, and the radial direction of the elastic roll A (Z direction) is parallel to the thickness direction described above. Note that "parallel" does not only mean strictly parallel, but also includes cases where the angle between the two directions is 10° or less. The angle may be 5° or less.

Next, the uncoated portion pressing process will be described with reference to FIG. 5. FIG. 5(a) is a schematic side view of the uncoated portion pressing process as viewed from the second direction and the axial direction of the metal foil. FIG. 5(b) is a schematic front view of FIG. 5(a) as viewed from the first direction D of the precursor sheet. Also, FIGS. 5(c) and (d) are views of the precursor sheet and elastic roll observed from the thickness direction ((FIG. 5(b) observed from the top and bottom of the paper).)

As shown in Figures 5(a) and (b), in the uncoated portion pressing process, the precursor sheet 10 is conveyed in the first direction D while passing the precursor sheet 10 between a predetermined pair of elastic rolls 20A and 20B, and the uncoated portion 3 (metal foil 1) is roll-pressed while applying a compressive force that presses the elastic rolls 20A and 20B against both sides of the precursor sheet in the thickness direction. The elastic roll 20 usually has a roll shape with an elastic body 22 arranged around a shaft body 21.

The material of the shaft body is not particularly limited, but a material with a larger Young's modulus than the elastic body is preferable. Examples of materials for the shaft body include metal.

It is preferable that the elastic body has a predetermined Young's modulus. The Young's modulus is 11.1 MPa or more and 86.1 MPa or less. If the Young's modulus is too low, the deformation amount of the elastic body may become too large, and excessive deformation force may be applied to the uncoated parts. As a result, breakage may not be sufficiently suppressed. On the other hand, if the Young's modulus is too high, the deformation amount of the elastic body may become too small, and sufficient deformation force may not be applied to the uncoated parts.

The material of the elastic body is not particularly limited, but examples include rubber, urethane, and other resins.

In the present disclosure, as shown in FIG. 5(b), in the axial direction X of the shaft body 21, the length XL ₁ of the elastic body 22 of the elastic roll A (20A) is preferably shorter than the length XL ₂ of the elastic body 22 of the elastic roll B (20B). The ratio of XL ₁ to XL ₂ (XL ₁ /XL ₂ ) is, for example, 0.1 or more and 0.5 or less. Note that the elastic roll A in FIG. 5(b) has two elastic bodies 22 for one shaft body 21. XL ₁ is the length per one elastic body 22. In the present disclosure, the axial direction of the shaft body of the elastic roll A and the axial direction of the shaft body of the elastic roll B are parallel to each other.

In addition, as shown in FIG. 5(b), the shape of the elastic roll may be such that one of the pair of elastic rolls (elastic roll A) is a stepped roll, and the other elastic roll (elastic roll B) is a non-stepped roll (a roll in which the entire axial direction of the shaft body is covered with an elastic body: a cylindrical roll). In particular, as shown in the above-mentioned FIG. 4(b) and FIG. 5(b), it is preferable that the elastic roll A is a stepped roll. For example, when the elastic roll B is a cylindrical roll, it is possible to suppress the deflection occurring in the precursor sheet and suppress the occurrence of wrinkles. On the other hand, both the elastic roll A and the elastic roll B may be stepped rolls. Even in this case, it is preferable that the elastic rolls A and B satisfy the above-mentioned relationship XL ₁ /XL ₂ .

In the uncoated portion pressing step, when observed from the thickness direction, as shown in Figures 5(b) and (c), the elastic body 22 of the elastic roll A (20A) has a first end _E1 and a second end _E2 disposed outside the first end _E1 in the axial direction X of the rotation shaft, and when observed from the thickness direction, it is preferable that the position of the first end _E1 overlaps the position of the elastic body 22 of the elastic roll B (20B). Note that the first end is a portion including the above-mentioned third side, and the second end is a portion including the above-mentioned fourth side.

As shown in Figs. 5(b) and (c), the elastic roll A (20A) is preferably arranged such that, when observed from the thickness direction, the elastic body 22 is in contact with the precursor sheet 10 at a position overlapping the uncoated portion 3, and the elastic roll A (20A) is arranged not to contact the precursor sheet 10 at a position overlapping the coated portion 2. In this case, as shown in Figs. 5(b) and (c), the elastic roll A (20A) has a first contact portion C ₁ in which the elastic body 22 is arranged at a position overlapping the uncoated portion 3, and has a non-contact portion N ₁ that does not contact the precursor sheet (coated portion 2 in Fig. 5(b)) at a position overlapping the coated portion 2. Note that, when the coated portion is arranged only on one side of the metal foil, the non-contact portion N ₁ may be a portion of the precursor sheet that does not contact the metal foil during roll pressing. Furthermore, the non-contact portion N ₁ is typically a portion where no elastic body is arranged. The elastic body in the first contact portion _C1 comes into contact with the uncoated portion 3 in the uncoated portion pressing process. On the other hand, the non-contact portion N1 does not usually come into contact with the precursor sheet in the uncoated portion pressing process. As shown in Figures 5(b) and 5(c), the elastic roll A (20A) has a first contact portion _C1 on each end of the non-contact portion _N1 in the conveying direction of the precursor sheet (the front-to-rear direction of the paper in Figure 4(b)).

As shown in Figs. 5(b) and (d), it is preferable that the elastic roll B (20B) is arranged so that the elastic body 22 contacts the precursor sheet 10 at a position overlapping the uncoated portion 3 when observed from the thickness direction, and the elastic body 22 contacts the precursor sheet 10 at a position overlapping the coated portion 2. In this case, as shown in Figs. 5(b) and (d), the elastic roll B (20B) is provided with a second contact portion C2 in which the elastic body 22 is arranged at a position overlapping the uncoated portion 3 when observed from the thickness direction, and a third contact portion C3 in which the elastic body ₂₂ contacts the precursor sheet (the coated portion 2 in Fig. 5(b)) at a position overlapping the coated portion ₂ when observed from the thickness direction. The elastic body at the second contact portion C2 contacts the uncoated portion 3 in the uncoated portion pressing process. On the other hand, the third contact portion _C3 contacts the coated portion in the uncoated portion pressing process.

It is also preferable that elastic roll A is an elastic roll that applies a compressive force from the upper side of the precursor sheet, and elastic roll B is an elastic roll that applies a compressive force from the lower side of the precursor sheet.

4. Electrode In the electrode manufactured by the method of the present disclosure, an electrode layer is formed on at least one surface of the metal foil. The electrode layer is a layer obtained by pressing the coated portion. The electrode manufactured by the method of the present disclosure may be a positive electrode or a negative electrode. In other words, the electrode layer may be a positive electrode layer or a negative electrode layer.

The metal foil typically functions as a current collector. That is, the metal foil may be a positive electrode current collector or a negative electrode current collector. When the metal foil is a positive electrode current collector, examples of the material of the metal foil include Al, SUS, and Ni. When the metal foil is a negative electrode current collector, examples of the material of the metal foil include Cu, SUS, and Ni.

The electrode layer contains at least an active material. When the electrode layer is a positive electrode layer, the active material is a positive electrode active material. The positive electrode active material is typically an oxide active material. Examples of the oxide active material include rock salt layer type active materials such as LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , LiVO ₂ , and LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , spinel type active materials such as LiMn ₂ O ₄ and Li (Ni _0.5 Mn _1.5 ) O ₄ , and olivine type active materials such as LiFePO ₄ , LiMnPO ₄ , LiNiPO ₄ , and LiCuPO ₄ .

When the electrode layer is a negative electrode layer, the active material is a negative electrode active material. Examples of the negative electrode active material include carbon active material, oxide active material, and metal active material. Examples of the carbon active material include mesocarbon microbeads (MCMB), highly oriented graphite (HOPG), hard carbon, and soft carbon. Examples of the oxide active material include Nb ₂ O ₅ , Li ₄ Ti ₅ O ₁₂ , and SiO. Examples of the metal active material include In, Al, Si, and Sn.

The electrode layer may also contain at least one of a conductive material and a binder, if necessary.

Examples of conductive materials include carbon materials, metal particles, and conductive polymers. Examples of carbon materials include particulate carbon materials such as acetylene black (AB) and ketjen black (KB); and fibrous carbon materials such as carbon fiber, carbon nanotubes (CNT), and carbon nanofibers (CNF). Examples of binders include fluorine-containing binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), rubber-based binders such as butadiene rubber, and acrylic-based binders.

The use of the electrodes in this disclosure includes, for example, Li-ion batteries. The battery in this disclosure may also be a liquid-based battery in which the electrolyte layer contains a liquid electrolyte (electrolytic solution). The use of the batteries in this disclosure is not particularly limited, but may include, for example, power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline-powered vehicles, and diesel-powered vehicles. In particular, it is preferable to use the batteries as driving power sources for hybrid electric vehicles, plug-in hybrid electric vehicles, or electric vehicles. The batteries in this disclosure may also be used as power sources for moving objects other than vehicles (for example, railways, ships, and aircraft), and may also be used as power sources for electrical appliances such as information processing devices.

This disclosure is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and anything that has substantially the same configuration as the technical ideas described in the claims of this disclosure and has similar effects is included within the technical scope of this disclosure.

[Experimental Example 1]
A rubber (elastic body) having a predetermined Young's modulus was prepared. Using an autograph device, a jig was repeatedly pressed against the rubber and returned to its original position, and the stress generated during this process was measured. The results are shown in Figure 6(a).

As shown in Figure 6 (a), it was confirmed that the first load creates permanent strain in the rubber, and that the second and subsequent loads do not create stress until the jig moves by the magnitude (depth) of the strain due to the effect of the strain. In this way, it was confirmed that permanent strain occurs in the elastic body when roll pressing is performed using an elastic body.

[Experimental Example 2]
A CAE analysis was performed to simulate the shear stress applied to the electrode sheet in the case where the first connecting portion and the second connecting portion were not provided in the elastic roll A and in the case where the first connecting portion and the second connecting portion were provided in the elastic roll A. The result in the case where the first connecting portion and the second connecting portion were not provided is shown in Fig. 6(b), and the result in the case where they were provided is shown in Fig. 6(c).

As shown in Figures 6(b) and (c), when the specified first and second connecting parts were provided, the maximum value of the shear stress applied to the coating part was reduced on both the electrode sheet surface (top) and surface (bottom). In this way, it was confirmed that by using elastic roll A having the specified first and second connecting parts, the shear stress applied to the coating part was reduced, and the occurrence of breakage and streaks when riding on the coating part could be suppressed.

Reference Signs List 1 metal foil 2 coated portion 3 uncoated portion 10 precursor sheet 21 shaft 22 elastic body 20 elastic roll 20A elastic roll A
20B…Elastic roll B

Claims (4)

A preparation step of preparing a precursor sheet having a metal foil having a longitudinal direction in a first direction and a coated portion and an uncoated portion disposed on the metal foil;
a coated portion pressing step of pressing the coated portion in a thickness direction while conveying the precursor sheet in the first direction;
an uncoated portion pressing step of pressing the uncoated portion in the thickness direction while transporting the precursor sheet in the first direction, before or after the coated portion pressing step;
having
The coated portion contains an electrode material including at least an active material,
the uncoated portion does not contain the electrode material and is disposed at an end of the coated portion in a second direction perpendicular to the first direction,
In the uncoated portion pressing step, a pair of elastic rolls having a shaft body and an elastic body covering the shaft body are used to perform roll pressing while applying a compressive force that presses the uncoated portion in the thickness direction,
As the pair of elastic rolls, an elastic roll A and an elastic roll B are used,
The elastic roll A has an elastic body A as the elastic body,
The elastic roll B has an elastic body B as the elastic body,
The elastic body A of the elastic roll A is
When viewed in a cross section along the rotation axis of the elastic roll A, the elastic roll A has a first side, a second side opposite to the first side, a third side extending in a direction intersecting the first side and the second side, a fourth side opposite to the third side, a first connecting portion connecting the first side and the third side, and a second connecting portion connecting the second side and the third side,
When a boundary between the first side and the first connecting portion is defined as _P1 and a boundary between the third side and the first connecting portion is defined as _P2 , the first connecting portion is a straight line connecting the _P1 and the _P2 ,
When a boundary between the second side and the second connecting portion is defined as _Q1 and a boundary between the third side and the second connecting portion is defined as _Q2 , the second connecting portion is a straight line connecting _Q1 and _Q2 ,
During the roll press,
The elastic roll A is disposed so that the third side is located closer to the coating section than the fourth side,
the elastic roll A is disposed such that, when observed from the thickness direction, the elastic body A comes into contact with the precursor sheet at a position overlapping the uncoated portion, and the elastic roll A has a portion that does not come into contact with the precursor sheet at a position overlapping the coated portion,
the elastic roll B is positioned such that, when observed from the thickness direction, the elastic body B contacts the precursor sheet at a position overlapping the uncoated portion, and also such that the elastic body B contacts the precursor sheet at a position overlapping the coated portion . The method for manufacturing an electrode according to claim 1 , wherein the elastic roll (B) is a stepped roll or a non-stepped roll including the elastic body (B) that does not have a C-chamfered structure. The method for manufacturing an electrode according to claim 1 , wherein a length of the elastic body A of the elastic roll A is shorter than a length of the elastic body B of the elastic roll B in the axial direction of the rotation shaft. When observed from the thickness direction, the elastic body A of the elastic roll A has a first end portion and a second end portion disposed outward from the first end portion in an axial direction of the rotation shaft,
The method for manufacturing an electrode according to claim 1 , wherein a position of the first end portion overlaps a position of the elastic body B of the elastic roll B when observed from the thickness direction.